1. Field of the Invention
The present invention relates to an elevator system using linear motors as driving devices in which self running type elevator cars can move in both vertical and horizontal directions and a plurality of such self running type elevator cars can be operated simultaneously within a single travelling corridor.
2. Description of the Background Art
Apart from a hydraulic type elevator system in which an elevator car is moved up and down by using a hydraulic plunger and a hoisting drum type elevator system used for a relatively small capacity purpose, a type of an elevator system most widely used conventionally is that in which an elevator car and a balance weight are suspended on opposite ends of a rope in which a single elevator car is operated to move up and down through a single travelling corridor, as shown in FIG. 1.
In this type of a conventional elevator system shown in FIG. 1, an elevator car 1 and a balance weight 2 are provided between guide rails 3 and guide rails 4, respectively, located within a travelling corridor, and they are suspended on opposite ends of a rope 8 through a sheave 6 and a bending sheave 7 of a hoisting machine 5 located in a machine chamber provided above the travelling corridor. In recent years, a three-phase induction motor is used for a driving device and an inverter device using a micro-processor is used for a control device in such a conventional elevator system.
This conventional elevator system shown in FIG. 1 has an advantage that the driving device and the control device of small size can be used so long as it is possible to provide a driving power for moving the elevator car 1 which is equivalent to the weight difference between the balance weight 2 and the elevator car 1 apart from the mechanical running loss, and moreover it is quite reliable because the techniques related to the performance and the safety of such a conventional elevator system have already been very well established through the extensive practical use in the past.
However, in recent years, there has been a number of propositions for a new type of elevator system in view of a possible future use in a super multistory building.
One type of the recently proposed new elevator systems is that in which no rope is used and a self running elevator car is used, where the elevator car can move not only in up and down directions but also in horizontal directions.
The concept of such a self running type elevator system is highly respected as a revolutionary technique which can make a breakthrough in a conventional preconception of one elevator car per one travelling corridor in an elevator system.
An exemplary overall configuration of such a self running type elevator system is shown in FIG. 2, in which a plurality of elevator cars 9 are provided in a plurality of vertical and horizontal travelling corridors, where each of a plurality of elevator cars 9 is equipped with a secondary conductor 10 of a linear motor, and each travelling corridor is equipped with a primary coil 31 of a linear motor, such that the driving force is obtained by the magnetic forces produced between the primary coil 31 and the secondary conductor 10 of the linear motor. Each elevator car 9 is further equipped with a brake 12 for stopping the motion of the elevator car 9, a shock absorber 13 for absorbing the shock due to the collision of the neighboring elevator cars 9, and a superconducting magnet 14 provided inside or below the shock absorber 13 for coupling the neighboring elevator cars 9.
In this elevator system of FIG. 2, the travelling corridor at the top floor is also equipped with a suspending machine 15 for catching and suspending the elevator car 9 reaching to the top floor, and a movable plate member 16 for enabling the horizontal running of the elevator car 9 on the top floor level, while the travelling corridor at the bottom floor is also equipped with a hydraulic jack 17 having a plate member for supporting the elevator car 9 reaching to the bottom floor and allowing the horizontal running of the elevator car 9 on the bottom floor level.
As for a control system for controlling power supply to each elevator car in such a self running type elevator system using linear motors, a system shown in FIG. 3 has been conventionally proposed.
In this control system shown in FIG. 3, the primary coil 31 provided on each travelling corridors A to Z is divided into a plurality of sections 1 to X, and a control device 32 for controlling power supply is provided for each j-th section of each i-th travelling corridor, where each control device 32 is equipped with a section selection switch 33 for each one of the elevator cars a to y. In a case the k-th elevator car is to run through the j-th section of the i-th travelling corridor, the ijk-th section selection switch 33 is activated by the ij-th control device 32 such that the current is supplied to the jk-th primary coil 31 in order to drive the k-th elevator car through the j-th section of the i-th travelling corridor.
However, in such a conventionally proposed control system for the self running type elevator system using linear motors, the control device 32 for controlling the power supply must be provided for each section of each travelling corridor, so that as a number of the travelling corridors increases and a length of each travelling corridor becomes longer, an enormous number of control devices 32 would become necessary, and when the current supply lines are connected to each of these enormous number of control devices 32, an enormous number of main circuit current supply lines are also required, such that the size of the system inevitably increases enormously.